Automatic choke



y 3, 1940- J. E. ANTONIDIS 2,209,218

AUTOMATIC CHOKE Filed Feb. 13, 1937 INVENTOR J06]? Edward fill/4717127615 ATTORNEYS I engine and more particularly to that form of Patented July 23, 1940 I 2,209,218 AUTOMATIC CHOKE John Edward Antonidis, Anderson, 1116., assignor to General Motors Corporation, Detroit, -Mich., a corporation of Delaware muses February 13, 1937, Serial No. 125,1537

- 12 Claims. (o1."123 119 the magnet will be effective to hold the air valve open to the desired degree notwithstanding a drop in suction. f

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred embodiment of the present invention is clearly shown; The figure is a vertical section through a device constructed in accordance with the present invention and showing the carburetor with which the device is incorporated in more or less dia grammatic form.

Referring to the drawing, the deference char,-

UNITED'VSTATES PATENT oFnce The present invention relates to means for controlling. automatically the ratio of fuel and air in the combustible mixture supplied by the carburetor ofan internal combustion engine to such device in which an automatic air or choke valve is provided which iscontrolled jointly by the action of a thermally responsive element and a suction operated device to modify the effect of such thermally responsive element.

Devices-of this same character have been designed heretofore in which an unbalanced air valve is provided at the air intake of the carburetor which the flow of ingoing air tends to open and thermally responsive means are proacter l0 indicates the body of the carburetor vided which are operative to-hold such air valve which is provided with an air intake l2 controlled closed at low temperatures to facilitate starting. byranunbalanced air valve l4 secured to a shaft A suction operated element is provided which is 16 which is off-set as shown in the drawing in operable'whe'n the engine starts to run to move such a way that the flow of air into the carburetor the air valve toward open position to prevent the tends to open the valve. The carburetor is pro- 20 formation of a too rich mixture when the engine vided with a float chamber l8 to which fuel is is running under its own power. It has been supplied through a conduit 20 and the flow of found that upon opening of the throttle and the such fuel is controlled by a valve 22 carried by a consequent reduction of engine suction, this 5110- float 24 which is operative to maintain a constant tionoperated means is inoperative to hold the level of fuel inthe chamber [8 in the conventional 25 air valve open sufiiciently and during the warmmanner. Fuel is supplied to the manifold-pasing up period, the thermostat is likely to move sage within the port of the carburetor through a the valve to vary the closed position, with the nozzle 26 which terminates adjacent the most result that under such operating conditions, the restricted portion of a Venturi tube 28 formed mixture would become too rich and cause loading in the mixture passage and the flow of mixture 30 of the engine. i from the carburetor is regulated by a throttle More specifically, it is an "object of the present valve 30 secured to a shaft 32 journalled in the invention to provide means to prevent the closing carburetor body l0 and operated in the usual of the air valve suff ciently to bring about the manner. difficulty referred to upon opening ofthe throttle The carburetor is secured in the conventional 35 with a consequent reduction of suction, or in manner to an intake manifold 34 which has a other words, an additional means other than the vertical riser pipe 36 extending upwardly. fromsuction operated member is provided which will the carburetor and surrounding this pipe is a hold the air valve open to the proper degree when chamber 38 through which exhaust gases are in; the engine runs under its own power, even if the tended to pass and which constitutes what is 40 suction effective on the suction operated device generally known in the art as a hot spot. .The falls to such a degree that the suction is not control unit for regulating the movement of the suficient to accomplish this function. air valve [4 is secured to a plate 40 which is- According to the present invention, this object adapted to be secured directly to the hot spot 'by is' attained by the provision of an electromagnet machine screws 42 and secured to this plate 38 45 which is effective upon the suction operated piston in any desirable way, is a housing 44 within tohold the latter in the position to which it is which a thermostat, hereinafter more specifically moved by a high suction even if the throttle is described, is positioned. The plate 40 has an opened and to prevent the return of the air valve opening 46 which registers with an opening 48 toward its closed position sufficiently to cause too formed in the housing 44 to permit the direct 50 great enrichment of the mixture under the radiation of heat from the wall of the hot spot to operating conditions referred to. This electroeffect the heating of the thermostat in accordance magnet is energized by the generator when the with the temperature. of the hot spot. engine is operated at a predetermined speed so I It will be understood that the housing 44 could that when the engine is operating at such speed,

be secured directly to the exhaust manifold rather QII than attached to a hot spot around the riser of the intake manifold as shown, the specific location of the control unit with reference to the heating chamber not being a part of this invention..

The valve I4 is adapted to be operated by an arm 50 which is secured to the shaft I6 and is pivotally connected with a link 52 extending upwardly to an arm 54, which is secured to a shaft 56 journalled in the housing 44 for rotation. Connected at one end to this shaft is a coil thermostat 58 of bimetallic type, the other end" of which is secured to the lower end of a link 60,

the'upp'er end of which is pivotally connected to a short arm 62 which extends downwardly from and is secured to a piston 64, which is formed of steel and is slidable within a cylinder 66 of brass or some ,other non-magnetic "material. This cylinder is positioned above the housing 44 and is secured thereto by a retaining collar which lies above a flange 68 formed" at the lower endof the cylinder and is held in position with respectto the housing 44 by a screw"!!! which extends through the'collar and is threaded into the'wallof-thej housing 44" as shown in the drawing. i v 1 The piston above referred to is normally held in the bottom of the cylinder in whichit slides by aspringTZ which is received between 'the end of the piston and a magnetc'onstruction hereinafter" more fully described and the piston is adapted to be "lifted by theaction of engine suction when the throttle valve is closed and the I suction between such valve and the engine is high, a suction passage'being provided between the riser of themanifold and the cylinder 66 for this purpose. As shown in the drawing, this suc t-ion passage'or conduit comprises a bore: I6 formed in the wall of theriser'of the manifold whichcommunicateswith a tube 18 which extends" into a nipple BO'screWed into a plug 82 whichis screwed into the top of cylinder 65, packing washer 84 being provided to prevent leakageat the joint between the plug andcylinder.

A-'-stufiing box 86 sur'rounds'the tube 18 and is screwedinto the n'ipplellll to form a leak-proof joint between the tube and the nipple. The re-' cess in -which the nipple 86 is threaded connects directly with a passage .38 formed in the wall of plug'82 and this passage communicates with the interior of the cylinder 66 and the space 90 isprovided around the magnet hereinbefore referred to, to permitythe communication of. the suction from the passage 88 to the space within the cylinder immediately above thepiston 64.

Obviously, when engine suction is relatively high with thethrottle in closed or nearly closed position, the piston 64 is lifted and the lifting of the piston is effected through the thermostat, itself, and the linkage connecting the shaft 56 withthe.

' shaft I6: to movethe valve toward open position.

=mined-bythe degree of temperature.

When. the engine is not running-and the temperatureis relatively low, the thermostat will hold the valveclosed with a: degree of pressure deterof the thermostat, which is connected to the link BG would remainfixed under such conditions and the contractingaction of thenthermostatdueto the variations in temperature would enablegsuch thermostat torotate the shaft 156v and. through V the connecting linkage above referred Qto, can move the valve toward closed position and hold it closed with a pressure depending uponthe. force of. .the. thermostat, which .in turn ,is dependent 1? upon .the engine temperature. When the engine One end begins to run, assuming that upon starting of the engine the valve is being held closed by the therpiston 64 pulls upwardly onthe end of the thermostat which is, attached to the link 60 and through the medium of the thermostat, itself, lifts the lever 54 to open the valve I4 to a degree dependent upon the movement of the piston under the influence of. suction and the degree of contraction of the thermostat at the time the lifting of the piston takes place.

As pointed out previously, if the' throttle is opened after the engine begins to run, the suction at the points between the throttle and the engine drops quickly and if the throttle is opened wide, this suction becomes almost negligible. As soon as this reduction in suction takes place, the

- spring 72 will move the piston 64 downwardly and through the medium of linkage previously described, would move the valve I4 toward closed position. If .such an action takes place, :thevalve M would restrict the admission of air .to the-car buretor to suchanextent that an' undesirable en.-f. richment of the mixture would occur,.t-he.mixture' becoming too rich to satisfactorily operatefthe engine and the engine-would,- therefore, loadiand run irregularly. To prevent this action ,ofqthe mo stat in the manner described, the lifting of the piston upon opening of the throttle duringthe warm-up period, the applicant hasprovided an electromagnet which he haspositioned within the cylinder 66 immediately above the piston .64, which is efiective to holdthe piston inits upper. position against the action of the spring when the throttle is opened as previously referred to. V f

Themagnet comprises a winding 92 which, when the device. is assembled, is held between-an end platev 94 atthe bottom of the winding and two plates 96 and 98 at the top of said winding, .the whole assembly being held in position. by a. bolt I00, which extends through all of theparts above described and also through an orifice I02 in theplug 82, the head of the bolt being received within the recess I04 formedin the plug .82 Ob One endof the magnet winding 92 is grounded through the connection .I I4 while the other end is connected by a wire H6 to a binding. post H8 which is secured in the wallof the plug 82 and is separated therefrom by alsleeve of insulating,"

material I25). The binding post II8 is connected by a wire I22 to a. wire I24 leading to the winding. I26 of the usual cut-out relay indicated in its, entirety by the reference number I30. The winding I26 is co'nnected'witha movable contact I32 which cooperates with a fixed contact I34 connected bywire I36 with a battery I38 grounded by the connection I40. Thewire I22 leads to the generator I42 which is grounded at I44 and.; the winding I26 is'grounded by the connection- The operation of t e above described mechanism should beentirelysobvious. :.When the -en-..-, gine iswat rest: and the temperature relatively low, the parts arein the position shown in the, drawingwiththe valve I4 heldin closed position 751 by the actionof the thermostat. If-it be'assumed that the engine be started under these conditions as soon as it starts to run under its own power, the suction becomes effective on the piston to lift said piston and move the valve l4 toward open position. When the engine isoperating at a predetermined speed which, in conventional installations, is relatively low, the action of the generator energizes the cut-out relay and moves the contact I32 into engagement with the contact I34 which closes the circuit between the battery and the magnet winding 92,thus energizing-the magnet of which said winding is a part. When the piston 64 has been-lifted against the force of spring 12, by suction, as previously described, the magnet attracts such piston which is made of steel, and exerts a force thereon to hold it in its lifted position.

If, after-the engine is operating under its own power with the piston lifted and the magnet energized as described, the throttle is opened relatively wide,- thesuction drops to-an almost negligible quantity. If the magnet above the piston 64 were not employed, the force of the spring I2 and the thermostat would force the piston 64 downwardly far enough to close the valve 14 to a position Where the mixture would be too rich for engine operation. The force of the magnet, however, is such that this action is avoided and the valve is held in the proper open position to prevent the too great enrichment of the mixture above referred to. After the temperature of the engine rises sufiiciently, thethermostat holds the valve 14 in fully open position and the magnet really has no effect on the valve which would be held open by the thermostat without the magnetic action. It is during the warm up period in which the magnet is primarily useful to obtain proper mixture ratios.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims Which follow.

What is claimed is as follows:

1. In a charge forming device for internal combustion engines having a mixture passage, means for supplying fuel and air thereto to form a combustible mixture, and a throttle for controlling the flow of said mixture, mechanism for automatically controlling the proportions of fuel and air in said mixture comprising an elementfor controlling the admission of one of the components of said mixture to themixture passage, means for normally holding the .said element in position to enrich the mixture when the engine is not running at low temperatures, means operated by the engine for moving the said element toward a position to lean the mixture and another means operable by the engine for holding the said element in its mixture leaning position, said last named means being ineffective to move the said element from its mixture enriching position.

2. In a charge forming device for internal combustion engines having a mixture passage, means for supplying fuel and air thereto to form a combustible mixture, and a throttle for controlling the fiow of .said mixture, mechanism for automatically controlling the proportions of fuel and air in said mixturecomprising an element for controlling the admission of one of the components of said mixture to the mixture passage, thermally responsive means for normally holding the said element in position to enrich the mixture when the engine is not running at low temperaleaning position, said last named means being ineffective to move the said'element from it'smixture enriching position.

3. In a charge forming device-forinternal combustion engines having a mixture passage, means for supplying fuel and air thereto tofOrma-combustible mixture, and a throttle for controlling the flow of said mixture, mechanism for automatically controlling the proportions of fuel and air in saidmixture comprising an element forcontrolling the admission of one of the components of said mixture to the mixture passage, thermally responsive means for normally holding the said element in position to enrich the mixture when the engine is not running at low temperatures, suction operated means for moving the said" element toward a position to lean the mixture and another means operable by the engine independently of engine suction for holding the said element in its mixture leaning position, said last named means being ineffective to move the said element from its mixture enriching position.

4. In a chargeforming device for internal'combustion engines having a mixture passage, means for supplying fuel and air thereto to form a combustible mixture,and a throttle for controlling'the flow of said mixture, mechanism for automatically controlling the proportions of fuel and air in said mixture comprising an element for controlling the admission of one of the components of said mixture to the mixture passage, thermally responsive means for normally holding the said element in position to enrich the mixture when the engine is not running at low temperatures; suction operated means for moving the said e1emen toward a position to lean the mixture and means operable by the generator for holding the said element in its mixture leaning position, said last named means being ineffective to move the said element from its mixture enriching position.

5. In a charge forming device for internal combustion engines having a mixture passage,means for supplying fuel and air thereto to form a combustible mixture, anda throttle for controlling the flow of said mixture, mechanism for auto v matically controlling the proportions of fuel and air in said mixture comprising an'element for controlling the admission of one of the components of said mixture tothe mixture passage, thermally responsive means for normally holding the said'element in position to enrich the mixture when the engineis not running at low temperatures, suctionoperated meansfor moving the said element toward a position to lean the mixture and means operablemythe generator, when operatingvat a. predetermined speed for holding the said element'in its'mixture leaning position, said last named means being ineffective to move the said element from its mixture enriching position.

6. In a charge forming device for internal combustion engines having a mixture passage, means for supplying fuel and air thereto to form a combustible mixture, and a throttle for controlling the flow of said mixture, mechanism for automatically controlling the proportions of fuel and air in said mixture comprising an element for controlling the admission of one of the components of said mixture to the mixture passage, means for normally holding the said element in position to enrich the mixture when the engine is not running at low temperatures, means oper- '7. In a charge forming device for internal combustion engines having a mixture passage, means .for supplying fuel and air thereto to form acombustible mixture,mechanism for automatically controlling the proportions of fuel and air-in said mixture, said mechanism comprising an element for controlling the admission of one of the components of said mixture to the mixture passage, thermally responsive means for holding I said element in position to enrich the mixture when the temperature is low andthe engine inoperative, engine operated meansfor moving said element toward a position to lean the mixture when the engine is started under such low temperature conditions, and another=engine' operated means for maintaining said element in its mixture leaning position while the engine is operating under its own power, a

8. In a charge forming device for internal combustion engines having a mixture passage, means for supplying fuel andair thereto to form a combustible mixture, mechanism .for automatically controlling the proportions of fuel and air in said mixture, said mechanism comprising-an element forcontrolling the admission of one of the components of said mixture to saidmixture passage, thermally responsive means forholding said element in position to enrich the mixture when the temperature is lowand the engine inoperative, means operable by engine suction for moving said elementtoward a position to lean the mixture whenthe engine is startedunder such low temperature conditions, and another engine operated means for controlling the position of said element independently of the engine "suction.

' 9. In a charge forming device for internal cornbustion engines having a mixturev passage, means for supplying fuel and air thereto to form a combustible mixture, mechanism for automatically controlling the proportions of fuel and air in said mixture, said mechanism comprising an element for controlling the admission of one of the components offsaid mixture to said mixture passage,

thermally responsive means for holding said element in position to enrich the mixture when the temperature is low andthe engine inoperative, a generator, means operable by engine suction for moving said element toward a position to lean the mixture when theengine is started under such low temperature conditions, and means operable by the generator for also controlling the position of said element; 7

10.fIn 'a charge forming device for internal combustion engines vhaving a mixture passage; means-for supplying fuel and air thereto to form a combustible mixture, mechanism. for auto-matically controlling the proportions of fuel and air in said,;mixture, said mechanism comprisingan elementfor-controllingthe admission of one-of he'components'of said mixture to said mixture.

passage, thermallyrespo-nsive means for holding said element in position toenrich the mixture when the temperature is low and-the engine in-. operative, a generator, means operable by engine suction :for moving said element toward a position .to'ilean the mixture when the'engine; is started. "under .such ,low temperature conditions, andmeans operable by the generator for main: taining. said element in its mixture leaning position.r

11. In a charge forming device for internal combustion engines having a mixture "passage, means for supplying fuel and air thereto .to form a combustible mixture, mechanism for automati:

cally controlling the proportions of fuel and air in said mixture, said mechanism comprising an ele-v ment for controlling the admission of one of the components of said mixture to said mixture passage, thermally responsive means for holdingsaid element in position to enrich the mixture when I the temperature is low and the engine inoperative, a generator, an-electromagnetin circuit with said generator and energized thereby when the engine is in operation, and a piston connected to said element and operableby engine suction to moveisaid element to its mixture leaning position, said piston also comprising the armature of said electromagnet and being adapted to occupy a position so far from the magnet winding, when said element is in position to enrich the mixture, that the magnet is inefl'ective to move said element from such position.

- 12. In a charge forming device for an internal combustion engine having a mixture passage, means for supplying fuel and air thereto to form a combustible mixture, mechanism forautomatically controlling the proportionsof fuel and air in said mixture, said mechanism comprising an element for controlling the admission of one of the components of said mixtureto said mixture passage, thermally responsive means for exerting a force on said element, when the temperature is relatively. low, to hold said element in position to enrich the mixture, means responsive to the suction of the engine for moving said element toward a position to lean the mixture when the temperature is such that the thermally responsive means tends to hold said element in mixture enriching position and means responsive to engine speed for maintaining said element in its mixture leaning position after it has been moved thereto. a JOHN EDWARD ANTONIDIS. 

